Assuming the subsocial route towards eusociality, I show that selection favors worker habits (under haplodiploidy) provided the mutant workers are able to bias the sex ratio towards sisters and/or selectively substitute their sons for brothers. If the original workers are not able to do this, selection does not favor the habit. However, under these conditions, selection is indifferent as to whether an individual rears offspring or sibs. This makes it easy for a mother to enlist her daughters services in rearing other offspring, since the daughter cannot evolve to stop the parental parasitism. These results deal with the origin of eusocial behavior. I also look at selection acting on genes (to invest in offspring rather than sibs) in existing eusocial societies. It is shown that selection for laying workers in very strong, even if such workers give up rearing a seemingly advantageous combination of brothers and sisters. This poses distinct problems for the maintenance of eusocial societies.
Journal of Theoretical Biology
eusocial behavior, parental parasitism
Journal of Theoretical Biology 75:451-465